Up until quite recently most dispensing cartridges of the type commonly employed as refills for manually operated grease guns were constructed from a paper laminate in tubular form. The cartridge body would then be fitted at either end with a metal cap which could either be completely removed or have a removable portion as required for grease gun dispensing. This prior art construction, although quite economical, has a tendency to leak and become messy under prolonged shipping and storage conditions. This deficiency has prompted the search for a packaging improvement in the grease cartridge field.
One approach recently advanced involves molding such dispensing cartridges from synthetic plastic material. While this change in the packaging material markedly improves on sealability it, at the same time, introduces a substantial material cost factor. This added material cost, unless compensated for in the overall design of the plastic dispensing cartridge, weighs heavily against its commercial acceptance. In this regard, the prior art attempts have failed to offer a cartridge construction capable of manufacture under maximum labor saving conditions but have instead had to rely on costly secondary manufacturing operations which involved the steps of perforating and resealing the closed end of the cartridge subsequent to molding.